JP7093977B2 - Heat generation material, heat generation system using it, and heat supply method - Google Patents

Description

The present invention relates to a heat generating material, and a heat generating system and a heat supply method using the heat generating material.

Conventionally, a heat utilization system using a hydrogen storage material that stores hydrogen at a high temperature (100 ° C. or higher) is known.

For example, Claudio Corgnale et al., Renewable and Sustainable Energy Reviews, 38 (2014) 821-833 propose a concentrating solar power generation system with two hydrogen storage materials. In this system, during the daytime when sunlight is available, the heat of the sun is used to generate water vapor to generate electricity from the turbine. At the same time, by heating the first (for high temperature) hydrogen storage material using a part of the solar heat, hydrogen is released from the first hydrogen storage material, and this hydrogen is used for the second (for low temperature). ) The hydrogen storage material is stored and the stored heat at that time is stored. On the other hand, at night when sunlight is not available, the second hydrogen storage material is heated by using the heat stored during the day to release hydrogen from the second hydrogen storage material. This hydrogen is stored in the first hydrogen storage material, and the storage heat at that time is used for the generation of water vapor. In this way, it is possible to generate electricity by the turbine by constantly generating water vapor not only during the day but also at night.

In the technique described in Claudio Corgnale et al., Renewable and Sustainable Energy Reviews, 38 (2014) 821-833, it is possible to efficiently utilize solar heat by using a hydrogen storage material as described above. .. However, in order to increase the calorific value at night when sunlight is not available, it is necessary to develop a material with higher hydrogen storage performance and larger calorific value. Further, in the conventional hydrogen storage material for high temperature, there is a problem that the particles of the hydrogen storage material are aggregated when hydrogen is released, and the hydrogen storage performance and the calorific value are deteriorated.

Therefore, an object of the present invention is to provide a heat-generating material which can suppress a decrease in hydrogen storage performance and calorific value when used at a high temperature, and further has improved physical properties such as hydrogen storage performance and calorific value. do.

The present inventors have made diligent studies to solve the above problems. As a result, it has been found that the above-mentioned problems can be solved by combining two kinds of metals satisfying predetermined conditions and using the hydrogen storage capacity of at least one of them as a heat generating material, and complete the present invention. It came to.

That is, according to one embodiment of the present invention, there is provided a heat generating material containing a first metal having a melting point of 230 ° C. or higher and a second metal having a melting point higher than that of the first metal. Here, in the heat generating material, at least one of the first metal or the second metal has a hydrogen solubility higher than that of silver at a temperature lower than the melting point of the second metal. Further, the hydride of at least one of the first metal or the second metal has a standard enthalpy of formation equal to or higher than the standard enthalpy of formation of CaH ₂ . The heat-generating material is characterized in that heat is generated when the first metal and the second metal come into contact with hydrogen gas at a temperature lower than the melting point of the second metal.

It is sectional drawing which shows typically the heat generating material which concerns on one Embodiment of this invention. The fine structure of the alloy contained in the heat generating material (heat generating material produced in Examples 1 and 2) according to the embodiment of the present invention is analyzed by using the elemental analyzer attached to the scanning electron microscope, SEM-EDX. It is a micrograph (magnification: 500 times) showing the result. It is sectional drawing which shows typically the heat generating material which concerns on another Embodiment of this invention. It is a block diagram which shows the outline of the heat generation system which concerns on one Embodiment of this invention. For the heat generating material (1) produced in Examples 1 and 2, differential scanning calorimetry (DSC) measurement (holding temperature 700 ° C.) under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow was performed. It is a graph which shows the result which performed. For the heat generating material (1) produced in Examples 1 and 2, differential scanning calorimetry (DSC) measurement (holding temperature 800 ° C.) under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow was performed. It is a graph which shows the result which performed. Regarding the heat generating material (1) produced in Examples 1 and 2, the change in hydrogen concentration at the time of temperature rise (that is, the profile of hydrogen occlusion and storage reaction) by the hydrogen TPR method (heat temperature reduction method). It is a graph which shows the result of having examined. FIG. 3 is a graph showing the results of differential scanning calorimetry (DSC) measurement under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow using nickel (Ni) powder in Comparative Example 1. FIG. 2 is a graph showing the results of differential scanning calorimetry (DSC) measurement under conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow using aluminum (Al) powder in Comparative Example 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

One embodiment of the present invention includes a first metal having a melting point of 230 ° C. or higher and a second metal having a melting point higher than that of the first metal, and at this time, the first metal or the first metal. At least one of the two metals has a higher hydrogen solubility than silver at a temperature below the melting point of the second metal, and the hydride of the first metal or at least one of the second metals. It has a standard production enthalpy equal to or higher than the standard production enthalpy of CaH ₂ , and generates heat when the first metal and the second metal come into contact with hydrogen gas at a temperature lower than the melting point of the second metal. It is a material. The heat generating material according to this embodiment is heated in the presence of hydrogen gas (H ₂ ) to release a very large calorific value to the outside. As described above, according to the present invention, there is provided a heat generating material capable of suppressing a decrease in hydrogen storage performance and calorific value when used at a high temperature, and further improving physical properties such as hydrogen storage performance and calorific value. Will be done. This heat generating material is suitably applied to a heat generating system and a heat supply method.

The mechanism by which the heat-generating material according to the present invention can generate a very large amount of heat (excessive heat) has not been completely clarified. However, the present inventors presume that, with respect to the above mechanism, a large amount of heat generation as described above is generated as a result of repeated occlusion and desorption of hydrogen due to repeated phase transitions of the hydride alloy.

[Heat-generating material]
FIG. 1 is a cross-sectional view schematically showing a heat generating material according to an embodiment of the present invention. The heat generating material 10 shown in FIG. 1 is an alloy of a first metal, aluminum (Al) (melting point: 660.3 ° C.) 20, and a second metal, nickel (Ni) (melting point: 1455 ° C.) 30. Contains 40. In the present embodiment, the alloy 40 of aluminum (Al) 20 and nickel (Ni) 30 has a plurality of phases having different composition ratios. FIG. 2 shows the fine structure of the alloy contained in the heat-generating material (heat-generating material produced in Examples 1 and 2) according to the present embodiment, using an elemental analyzer attached to a scanning electron microscope, SEM-EDX. It is a micrograph (magnification: 500 times) which shows the analysis result. As shown in FIG. 2, the alloy according to this embodiment has a plurality of phases having different composition ratios. Specifically, in the micrograph shown in FIG. 2, it can be seen that there are two phases, a phase showing light gray and a phase showing dark gray. Here, the graph shown on the left of FIG. 2 shows the result of analyzing the elemental composition of the light gray phase in the micrograph shown in FIG. 2, and from this result, the light gray phase is Al: Ni = 61. It can be seen that it has a composition of atomic%: 39 atomic% (Al: Ni = 3.12: 2 (atomic ratio)). On the other hand, the graph shown on the right of FIG. 2 shows the result of analyzing the elemental composition of the dark gray phase in the micrograph shown in FIG. 2, and from this result, the dark gray phase has Al: Ni = 76 atoms. It can be seen that it has a composition of%: 24 atomic% (Al: Ni = 3.16: 1 (atomic ratio)).

Hereinafter, the specific configuration of the heat generating material according to this embodiment will be described in detail.

(Type of metal)
The heat generating material according to this embodiment contains at least two kinds of metals. Among the metals contained in the heat generating material according to the present embodiment, those having a lower melting point are referred to as "first metal", and those having a higher melting point are referred to as "second metal". It is essential that the melting point of the first metal is 230 ° C. or higher. Further, at least one of the first metal and the second metal contained in the heat generating material according to the present embodiment has a hydrogen solubility higher than that of silver at a temperature lower than the melting point of the second metal. With such a configuration, hydrogen is sufficiently occluded for repeating the phase transition of the hydride alloy that occurs when the heat generating material according to this embodiment generates a large amount of heat. On the other hand, if the hydrogen solubility of both the first metal and the second metal is less than or equal to the hydrogen solubility of silver, the material cannot occlude a sufficient amount of hydrogen and cannot be used as a heat generating material. In a preferred embodiment, both the first metal and the second metal have greater hydrogen solubility than silver at the above temperatures. The value of hydrogen solubility in a certain metal may be a value obtained experimentally or a value obtained by calculation using a computer simulation.

Further, the hydride of at least one of the first metal or the second metal has a standard enthalpy of formation of CaH ₂ or more (-186.2 kJ / mol) or higher. With such a configuration, hydrogen is sufficiently stored for repeated phase transitions of the hydride alloy that occurs when the heat generating material according to this embodiment generates a large amount of heat. On the other hand, when the standard production enthalpy of each of the first metal and the second metal hydride is larger than the standard production enthalpy of CaH ₂ , the hydride produced by storing hydrogen is extremely stable in terms of energy. The hydrogen is not sufficiently stored from the hydride, and cannot be used as a heat generating material. The value of the standard enthalpy of formation of a hydride of a certain metal may also be a value obtained experimentally or a value obtained by calculation using a computer simulation.

When at least a metal satisfying the provisions of these "first metal" and "second metal" is contained, it shall be included in the technical scope of the heat generating material according to this embodiment. That is, even if three or more metals are contained, it is within the scope of the present invention if any two metals satisfy the above-mentioned provisions. Further, there is no particular limitation on the content form of these metals. However, as in the above-described embodiment, it is preferable that the first metal and the second metal exist in the state of an alloy having a plurality of phases having different composition ratios.

The specific types of the first metal and the second metal are not particularly limited, and can be arbitrarily selected from combinations that can satisfy the above provisions. Then, whether a certain metal corresponds to the "first metal" or the "second metal" is a relative one determined by the relationship with other metals to be combined. Therefore, depending on the combination of these metals, there is a possibility that a certain metal corresponds to the "first metal" and the case corresponds to the "second metal". As an example, examples of the first metal include aluminum (Al), tin (Sn), and lead (Pb). Examples of the second metal include nickel (Ni), titanium (Ti), zirconium (Zr), manganese (Mn), zinc (Zn), vanadium (V), and calcium (Ca). It is preferable to use these metals because it is possible to form a heat-generating material having a large calorific value. Further, from the viewpoint that tin (Sn) having a relatively low melting point can function as a heat generating material even when the heating temperature is relatively low, it is preferable to use tin (Sn) as the first metal. Further, from the viewpoint of large calorific value, it is also preferable to use aluminum (Al) as the first metal. Further, examples of the combination of "first metal-second metal" include nickel-zirconium, aluminum-nickel, aluminum-titanium, aluminum-manganese, aluminum-zinc, tin-titanium, aluminum-calcium and the like. In particular, from the viewpoint that it is possible to form a heat-generating material having a large calorific value, a combination of aluminum-nickel, aluminum-titanium, and tin-titanium is preferable, and a combination of aluminum-nickel and tin-titanium is more preferable. The aluminum-nickel combination is particularly preferred. Of course, metals other than these and combinations other than these may be used.

(Outer shell)
As shown in Example 8 (heating material (7)) and FIG. 3 described later, the heat-generating material according to this embodiment may be located inside an outer shell body made of an inorganic porous body. In the embodiment shown in FIG. 3, the metal (aluminum (Al) 20 and nickel (Ni) 30) is an outer shell made of a metal oxide (silica (SiO ₂ )) which is an inorganic porous body in the state of the alloy 40. It is located inside 50.

Here, the heat generating material according to this embodiment is used by being heated to a temperature lower than the melting point of the second metal. Therefore, the constituent material of the outer shell is not limited to silica, and is a porous body that is chemically stable at the above temperature under a hydrogen gas (H ₂ ) atmosphere and that allows hydrogen gas (H ₂ ) to permeate. All you need is. As the constituent material of such an outer shell, metal oxides such as silica, alumina, ceria, zirconia, titania, and zeolite are preferable, and silica or zirconia is particularly preferable, from the viewpoint of easy availability and production. Further, a porous carbon carbon material such as activated carbon, a porous silicon carbide / silicon nitride, a porous metal, a porous metal complex (MOF), or the like can also be used as an inorganic porous body constituting the outer shell.

As shown in FIG. 3, since the first metal and the second metal are located inside the outer shell body made of the inorganic porous body, there is an advantage that the heat generating material can be easily handled. Further, it is preferable that the first metal melts at the operating temperature of the heat-generating material (the temperature below the melting point of the second metal) (however, the exothermic reaction can proceed even if the first metal is not melted). It may be). Here, when the first metal is melted at the operating temperature of the heat-generating material, if the outer shell is present, the melted first metal is prevented from flowing and the shape of the heat-generating material cannot be maintained. be able to. If the shape of the heat-generating material is maintained in this way, there is an advantage that the heat-generating material is easy to handle even when it is reused.

The presence of the outer shell is not essential. That is, as shown in FIG. 1, the heat generating material 10 is composed of a mixture, a solid solution or an alloy of a first metal (for example, aluminum (Al)) and a second metal (for example, nickel (Ni)). May be.

[Manufacturing method of heat-generating material]
The method for producing the heat-generating material according to this embodiment is not particularly limited, and the heat-generating material according to this embodiment can be produced by referring to the conventionally known technical common sense based on the description in the column of Examples described later.

As an example, in order to produce the heat generating material of the embodiment shown in FIG. 3, the method described in the column of Examples described later can be adopted. This manufacturing method will be briefly described below by taking as an example the case where the outer shell is made of silica (SiO ₂ ).

In this manufacturing method, first, a powder of a first metal (for example, aluminum (Al)) is prepared. Water or a hydrophilic solvent containing water is added to this powder as a solvent. As the hydrophilic solvent, alcohol having 1 to 4 carbon atoms, formic acid, nitromethane, acetic acid, acetone, tetrahydrofuran, ethyl acetate, acetonitrile, dimethylformamide, dimethyl sulfoxide, propylene carbonate, N-methylpyrrolidone and the like can be used, and water can be used. There is no restriction on the content of. Next, a base is added as a catalyst for the silicification (hydrolysis / condensation) reaction described later. The type of this base is not particularly limited, and trimethylamine, triethylamine, tripropylamine, tributylamine, imidazole, N, N-dimethylaniline, N, N-diethylaniline, pyridine, quinoline, isoquinoline, α-picoline, β-picoline. , 2,4-Lutidine, 2,6-Lutidine and other organic base catalysts, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate and sodium hydrogencarbonate.

Then, if necessary, stirring treatment is performed to uniformly mix the solution, and then a coupling agent having an ability to adsorb to any metal is added, and this is used as a starting point for forming the silica outer shell. The coupling agent is preferably an alkoxide or a compound having an amino group such as an aminopropyl group. For example, aminopropyltrimethoxysilane, aminopropyltriethoxysilane (APTES), aminopropyltripropoxidesilane, aminopropyldimethoxymethylsilane, mercaptotrimethylsilane, mercaptotriethylsilane, mercaptodimethoxymethylsilane and the like are suitable. Further, in addition to the alkoxide having an amino group, diamines such as pentamethylenediamine, hexamethylenediamine and heptamethylenediamine can also be used. If necessary, the solution may be heated and further subjected to stirring treatment. According to the procedure so far, the coupling agent can be adsorbed on the surface of the metal particles or can be coated with the coupling agent. The formation of such an adsorption layer or a coating layer has a technical effect of enhancing the uniformity of the silica outer shell.

Then, in order to form a silica outer shell, a precursor thereof is added to cause an outer shell forming reaction. As the precursor of the silica outer shell, an alkoxide such as silicon tetramethoxydo, silicon tetraethoxydo (TEOS), or silicon tetrapropoxide, or an alkoxide in which the alkoxy group is partially changed to another functional group can also be used. can. Other functional groups include a methyl group, an ethyl group, a propyl group, an aminopropyl group, a mercapto group and the like. Further, sodium silicate (water glass) can also be used as the silica precursor. However, in that case, it is necessary to control the pH in the range of 12 to 14 to reduce the reactivity of the water glass. At this point, some alkoxides such as TEOS do not dissolve in water, so the solution is in a state of being separated into two layers (the lower layer is the aqueous solution phase and the upper layer is the silica precursor phase). When a hydrophilic solvent is used instead of water or a hydrophilic alkoxide is used as the solvent, such phase separation does not occur.

As a precursor for forming an outer shell made of alumina, zirconia, titania, magnesia, etc. other than silica, the same alkoxide as in the case of silica can be used. For example, aluminum propoxide, aluminum isopropoxide, aluminum butoxide, zirconium isopropoxide, zirconium butoxide, titanium isopropoxide, titanium butoxide, magnesium ethoxydo, magnesium methoxyd and the like can be used. Further, salts such as magnesium chloride, magnesium nitrate and magnesium sulfate can also be used as precursors of magnesia. Further, as the precursor of yttrium oxide, tungsten oxide, cerium oxide and lanthanum oxide, chlorides, nitrates, sulfates, inorganic acids and ammonium salts thereof of each metal can be used. For example, yttrium chloride, yttrium nitrate, yttrium sulfate, tungstic acid, ammonium tungstate, sodium tungstate, cerium chloride, cerium nitrate, cerium sulfate, lanthanum chloride, lanthanum nitrate, lanthanum sulfate and the like.

After the addition of the silica precursor, stirring is preferably performed with the solution warmed. As a result, the silica precursor slightly dissolved in the aqueous phase causes a silica formation reaction (hydrolysis / condensation reaction) in the presence of the above-mentioned base catalyst. As this reaction progresses, the silica precursor present in the aqueous phase is consumed, so that the silica precursor is continuously supplied from the silica precursor phase to the aqueous phase, and all the silica precursors are consumed. Silicaization (hydrolysis / condensation) reaction proceeds until.

After the silica outer shell is formed, a centrifugation treatment is performed for the purpose of separating the silica-coated first metal particles from the solution. Then, the particles may be washed once or multiple times with a solvent such as 2-propanol for the purpose of removing the base catalyst and the unreacted silane compound adhering to the separated silica-coated metal particles. Then, for example, it is preferably vacuum dried overnight and then calcined in the air at a temperature of 100 to 500 ° C. for 0.5 to 12 hours. As a result, the solvent remaining on the silica-coated metal particles can be removed, and the silica-forming reaction can be completely proceeded. In this way, composite particles are obtained in which the surface of the first metal particles is coated with silica, which is an inorganic porous body (metal oxide).

Subsequently, an aqueous solution containing a salt of the metal (for example, nitrate, hydrochloride, etc.) is added as a raw material of the second metal to the composite particles (silica-coated metal particles) obtained above, if necessary. Add with water. Next, the solution is impregnated for several hours to several tens of hours while being heated to 70 to 100 ° C. to allow ions of the second metal to penetrate into the pores of silica. Then, for example, it is vacuum dried overnight and calcined in hydrogen at 300 to 500 ° C. for 0.5 to 4 hours. Air or an inert gas can be used as the atmospheric gas at the time of firing, but in that case, it is necessary to reduce the atmosphere gas with hydrogen again at the same temperature and time after firing. As a result, the precursor of the second metal is reduced to the metal, and the heat generating material of the embodiment shown in FIG. 3 can be produced.

Next, a method for manufacturing a heat-generating material without using an outer shell will be briefly described below. In this manufacturing method, first, a first metal (for example, aluminum (Al)) powder and a second metal (for example, nickel (Ni)) powder are prepared. The shape of the metal does not necessarily have to be a powder, but it is desirable to have a powder shape for uniform mixing. Weigh the two types of powder in the desired ratio, add them to a mortar and pestle, and mix them with a pestle and the like. The material of the mortar, pestle, etc. may be any material such as agate and alumina.

Subsequently, the composite particles obtained above are heat-treated to be alloyed. It is not always necessary to alloy in advance, and the heating material may be alloyed during heating to generate heat. The method of alloying is not limited to heat treatment, but may be chemical alloy plating or mechanical alloying in which mechanical mixing is performed using a ball mill device.

If the particle size of the alloy becomes large after alloying, the particle size may be reduced by pulverization or the like.

[Use of heat-generating material (heat-generating system)]
The heat generating material according to the above-described embodiment can be used as a heat generating system applicable to various uses using heat. That is, according to another embodiment of the present invention, a heat generating device in which the heat generating material according to the above-described embodiment is arranged, a heater for heating the heat generating material, and a hydrogen gas supply for supplying hydrogen gas to the heat generating material. A heat generation system with a device is also provided. Further, the heat generating material according to the above-described embodiment is heated to a temperature equal to or higher than the melting point of the first metal and lower than the melting point of the second metal in the presence of hydrogen gas to generate heat of the heat generating material. Heat supply methods, including, are also provided.

FIG. 3 is a block diagram showing an outline of the heat generation system according to the present embodiment. As shown in FIG. 3, when the heat generating system is used (when heat is supplied), the hydrogen gas supply device supplies hydrogen gas to the heat generating material arranged in the heat generating device. Further, the heater heats the heat generating material arranged in the heat generating device. The heating temperature at this time is a temperature lower than the melting point of the second metal, but is preferably higher than the melting point of the first metal. As an example, when the "first metal-second metal" combination is aluminum-nickel, the heating temperature is less than 1455 ° C, preferably higher than 660.3 ° C. Further, when this combination is tin-titanium, the heating temperature is less than 1668 ° C, preferably higher than 231.9 ° C.

When the heat generation system is used (when heat is supplied), the heat generation material arranged in the heat generation device is heated to the above heating temperature in the presence of hydrogen gas (H ₂ ), so that a very large amount of heat generation is externally generated. Release to. The large amount of heat released from the heat generating material in this way is supplied to the heat consuming unit located outside the heat generating system. The mechanism by which the heat-generating material according to the present invention can generate a very large amount of heat (excessive heat) has not been completely clarified. However, from the result of examining the profile of the hydrogen storage reaction by the heat generating material (1) at the time of raising the temperature by the hydrogen TPR method (heating reduction method) in the column of Examples described later, the heat generating material (1) is made of aluminum (Al). It is suggested that the large heat generated when heated to a temperature higher than the melting point of the hydrogen storage reaction is different from the heat of hydrogen storage in the hydrogen storage reaction. Since a large amount of heat generated by the heat generating material according to the present invention occurs only in the presence of hydrogen gas (H ₂ ), the present inventors occlude hydrogen by repeating the phase transition of the hydride alloy as the mechanism of the heat generation. And as a result of repeated occlusion, it is presumed that a large amount of heat generation as described above will occur.

Here, the heat generating device in which the heat generating material is arranged can have an arbitrary configuration, and may be, for example, a container for holding the heat generating material (particularly, a particulate heat generating material). Further, the heat generating device has a honeycomb structure such as a ceramic honeycomb or a metal honeycomb in order to increase the contact area between the heat generating material and hydrogen gas (H ₂ ), and holds the heat generating material on the flow path surface of the honeycomb cell. You can also do it.

In order to supply the heat generated by the heat generating device to the heat consuming unit, the heat generating device and the heat consuming unit can be thermally coupled. In this case, heat is supplied from the heat generating device to the heat consuming part by heat transfer, heat is supplied from the heat generating device to the heat consuming part through the heated gas, and the heat consuming part is supplied from the heat generating part using a heat medium. Can supply heat to the. When a heat medium that is a fluid is used, the heat generating device can have a shape generally adopted as a heat exchanger. That is, the heat generating device can have a flow path in which the heat generating material is arranged and the hydrogen gas (H ₂ ) is circulated, and a flow path in which the heat medium is circulated. As the heat medium, a heating object itself such as cooling water can also be used.

The hydrogen gas supply device shall be provided with any device for supplying hydrogen gas, for example, a tank holding hydrogen gas, a pump and piping for obtaining hydrogen gas (H ₂ ) from the outside and supplying it to a heat generating material. Can be done. This hydrogen gas (H ₂ ) is for causing an exothermic reaction by being occluded by the exothermic material when the exothermic material arranged in the exothermic apparatus is heated. The hydrogen gas (H ₂ ) may be held in the tank in the state of hydrogen gas, or may be a gas generated at any time by, for example, reforming of methanol or biomass.

Hereinafter, the present invention will be described in more detail by way of examples. However, the technical scope of the present invention is not limited to the following examples.

[Example 1 and Example 2]
The heat generating material (1) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (1))
First, aluminum (Al) (melting point: 660.3 ° C.) powder (purity 99.5%) was prepared as the first metal. In addition, nickel (Ni) (melting point: 1455 ° C.) powder was prepared as the second metal. 20 mg of this aluminum (Al) powder and 20 mg of nickel (Ni) powder were weighed and mixed for 1 to 2 minutes using a mortar and pestle to prepare a heat-generating material (1) in the state of a mixture of metal powders.

(Measurement of differential scanning calorimetry (DSC) of heat generating material (1))
For the heat generating material (1) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow under the following measurement conditions.
・ DSC measurement conditions Sample amount: 40 mg
Temperature range: Room temperature to 800 ° C
Temperature rise rate: 5 ° C / min
Gas flow rate: H ₂ 120 mL / min, He 120 mL / min
Holding temperature: 250-800 ° C
Retention time: 2 hours-Procedure for DSC measurement Prior to the day before measurement, baseline measurement was performed on an empty sample using the same procedure as below;
As a pretreatment, vacuum degassing was performed until it became 10 ^-3 Pa or less (required time is 2 to 3);
A measurement was carried out in which the temperature was raised from room temperature to a predetermined temperature in a He or H ₂ air flow and maintained at that temperature.

The results of this DSC measurement are shown in FIGS. 5A and 5B, respectively. Here, FIGS. 5A and 5B show that the holding temperature during the DSC measurement is 700 ° C. (FIG. 5A) or 800 ° C. (FIG. 5B), which is higher than the melting point of aluminum (Al) and lower than the melting point of nickel (Ni). It is a graph which shows the result of the measurement performed by setting each of. It is considered that the heat generating material (1) obtained by such DSC measurement has a structure as shown in FIGS. 1 and 2 in the process of raising the temperature.

As shown in FIGS. 5A and 5B, when the temperature of the heat generating material (1) is raised to 700 ° C. or 800 ° C., a very large heat generation phenomenon (in the case of H ₂ flow as compared with the case of He flow) ( (Generation of excess heat) was continuously confirmed. That is, the heat generating material (1) has a very large heat generation phenomenon (excessive heat) due to the contact of these metals with hydrogen gas (H ₂ ) at a temperature lower than the melting point of the second metal, nickel (Ni). It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement is Δ = 66.5 [mW / g heat generating material] when the holding temperature is 700 ° C. (FIG. 5A), and the holding temperature is 800 ° C. In the case of (FIG. 5B), Δ = 176 [mW / g heat generating material]. These results are also shown in Table 1 below.

Regarding the heat-generating material (1) prepared above, the profile of the hydrogen storage reaction by the heat-generating material (1) at the time of temperature rise was investigated by the hydrogen TPR method (heating reduction method). The results are shown in FIG.

As shown in FIG. 6, the exothermic material (1) caused a hydrogen storage reaction in the range of 300 to 600 ° C., but the progress of the hydrogen storage reaction was not confirmed in the region above 700 ° C. From this, it was suggested that the large heat generated when the heat generating material (1) was heated was different from the hydrogen storage heat during the hydrogen storage reaction.

[Example 3]
The heat generating material (2) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (2))
The heat generating material (2) was prepared by the same method as in Example 1 described above, except that the zirconium (Zr) powder was used instead of the aluminum (Al) powder. Here, since the melting point of zirconium (Zr) is 1855 ° C., nickel (Ni) is the first metal and zirconium (Zr) is the second metal in the heat generating material (2).

(Measurement of differential scanning calorimetry (DSC) of heat generating material (2))
For the heat generating material (2) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above, except that the holding temperature was changed from 700 ° C. to 450 ° C.

When the temperature of the heat generating material (2) is raised to 700 ° C., which is lower than the melting point of (Zr), the heat generation phenomenon (generation of excess heat) is very large in the case of H ₂ flow as compared with the case of He flow. Was continuously confirmed. That is, the heat generating material (2) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of the second metal, zirconium (Zr). It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement was Δ = 13 [mW / g heat generating material].

[Example 4]
The heat generating material (3) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (3))
The heat generating material (3) was prepared by the same method as in Example 1 described above, except that titanium (Ti) powder was used instead of nickel (Ni) powder. Here, since the melting point of titanium (Ti) is 1668 ° C., aluminum (Al) is the first metal and titanium (Ti) is the second metal in the heat generating material (3).

(Measurement of differential scanning calorimetry (DSC) of heat generating material (3))
For the heat generating material (3) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above.

When the temperature of the heat generating material (3) is raised to 700 ° C., which is lower than the melting point of titanium (Ti), a very large heat generation phenomenon (excess heat generation) occurs in the case of H ₂ flow as compared with the case of He flow. ) Was continuously confirmed. That is, the heat generating material (3) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of titanium (Ti), which is a second metal. It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement was Δ = 36 [mW / g heat generating material].

[Example 5]
The heat generating material (4) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (4))
The heat generating material (4) was prepared by the same method as in Example 4 described above, except that tin (Sn) powder was used instead of the aluminum (Al) powder. Here, since the melting point of titanium (Ti) is 1668 ° C., tin (Sn) is the first metal and titanium (Ti) is the second metal in the heat generating material (4).

(Measurement of differential scanning calorimetry (DSC) of heat generating material (4))
For the heat generating material (4) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above.

When the temperature of the heat generating material (4) is raised to 700 ° C., which is lower than the melting point of titanium (Ti), a very large heat generation phenomenon (excess heat generation) occurs in the case of H ₂ flow as compared with the case of He flow. ) Was continuously confirmed. That is, the heat generating material (4) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of titanium (Ti), which is a second metal. It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement was Δ = 50 [mW / g heat generating material].

[Example 6]
The heat generating material (5) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (5))
The heat generating material (5) was prepared by the same method as in Example 4 described above, except that manganese (Mn) powder was used instead of titanium (Ti) powder. Here, since the melting point of manganese (Mn) is 1246 ° C., aluminum (Al) is the first metal and manganese (Mn) is the second metal in the heat generating material (5).

(Measurement of differential scanning calorimetry (DSC) of heat generating material (5))
For the heat generating material (5) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above.

When the temperature of the heat-generating material (5) is raised to 700 ° C., which is lower than the melting point of manganese (Mn), a very large heat generation phenomenon (excess heat generation) occurs in the case of H ₂ flow as compared with the case of He flow. ) Was continuously confirmed. That is, the heat generating material (5) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of the second metal, manganese (Mn). It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement was Δ = 60 [mW / g heat generating material].

[Example 7]
The heat generating material (6) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (6))
The heat generating material (6) was prepared by the same method as in Example 6 described above, except that calcium (Ca) powder was used instead of manganese (Mn) powder. Here, since the melting point of calcium (Ca) is 842 ° C., aluminum (Al) is the first metal and calcium (Ca) is the second metal in the heat generating material (6).

(Measurement of differential scanning calorimetry (DSC) of heat generating material (6))
For the heat generating material (6) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above, except that the holding temperature was changed from 700 ° C. to 600 ° C.

When the temperature of the heat generating material (6) is raised to 600 ° C., which is lower than the melting point of calcium (Ca), a very large heat generation phenomenon (excess heat generation) occurs in the case of H ₂ flow as compared with the case of He flow. ) Was continuously confirmed. That is, the heat generating material (6) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of calcium (Ca), which is a second metal. It was confirmed that it is a material that continuously indicates the occurrence of calcium. The excess heat (Δ) generated during the holding time in this measurement was Δ = 105 [mW / g heat generating material].

[Example 8]
The heat generating material (7) was prepared by the following method, and the differential scanning calorimetry (DSC) was measured.

(Preparation of heat generating material (7))
First, aluminum (Al) (melting point: 660.3 ° C.) powder (purity 99.5%) was prepared as the first metal. To 0.50 g of this aluminum (Al) powder, 25 mL of distilled water was added as a solvent. Next, 84 μL of triethylamine was added as a catalyst for the silicification (hydrolysis / condensation) reaction described later, and the mixture was stirred for 10 minutes to make the liquid phase portion uniform.

Then, 83 μL of APTES ((3-aminopropyl) triethoxysilane) was added, the solution was heated to 60 ° C., and the mixture was further stirred for 30 minutes. As a result, APTES was adsorbed on the surface of the particles of aluminum (Al) alone.

Then 5 mL of tetraethoxysilane (TEOS) was added. At this point, since TEOS was insoluble in water, the solution was in a state of being separated into two layers (the lower layer was the aqueous solution phase and the upper layer was the TEOS phase).

After the addition of TEOS, the solution was stirred at 60 ° C. for 2 hours. As a result, TEOS and APTES, which are slightly dissolved in the aqueous phase, undergo a silicification (hydrolysis / condensation) reaction in the presence of the above catalyst. As this reaction progresses, the TEOS present in the aqueous phase is consumed, so the TEOS is continuously supplied from the TEOS phase to the aqueous phase, and silicification (hydrolysis / condensation) is performed until all the TEOS are consumed. ) The reaction proceeded.

After completion of the silicification reaction, centrifugation (2000 rpm, 15 minutes) was performed for the purpose of separating the silica-coated aluminum (Al) particles from the solution. Then, the particles were washed with 2-propanol three times for the purpose of removing triethylamine and unreacted silica raw materials adhering to the separated silica-coated Al particles. Then, after vacuum drying for 12 hours, 2-propanol remaining in the silica-coated Al particles was removed by firing in air at 350 ° C. for 1 hour, and the silica-forming reaction was completely carried out. I made it progress. In this way, composite particles were obtained in which the surface of the Al particles was coated with silica, which is an inorganic porous body (metal oxide).

Subsequently, nickel nitrate (Ni (NO ₃ ) ₂ ), which is a compound containing nickel, which is a second metal having hydrogen storage capacity, with respect to 0.2812 g of the composite particles (silica-coated Al particles) obtained above. 2.095 mL of a 1 mol / L aqueous solution and 1 mL of distilled water were added. Next, the solution was impregnated overnight with the solution heated to 70 to 100 ° C. to allow nickel ions (Ni ²⁺ ) to penetrate into the pores of silica. Then, after vacuum drying for 12 hours, firing was performed at 350 ° C. for 1 hour in a hydrogen stream. As a result, nickel ions (Ni ²⁺ ) were reduced to a simple substance of nickel (Ni) (melting point: 1455 ° C.) to prepare a heat generating material (7).

It is considered that the heat generating material (7) thus prepared has a structure as shown in FIG.

(Measurement of differential scanning calorimetry (DSC) of heat generating material (7))
For the heat generating material (7) prepared above, differential scanning calorimetry (DSC) measurement was performed under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow under the following measurement conditions.
・ DSC measurement conditions Sample amount: 40 mg
Temperature range: Room temperature to 800 ° C
Temperature rise rate: 5 ° C / min
Gas flow rate: H ₂ 120 mL / min, He 120 mL / min
Holding temperature: 250-800 ° C
Retention time: 2 hours-Procedure for DSC measurement Prior to the day before measurement, baseline measurement was performed on an empty sample using the same procedure as below;
As a pretreatment, vacuum degassing was performed until it became 10 ^-3 Pa or less (required time is 2 to 3);
A measurement was carried out in which the temperature was raised from room temperature to a predetermined temperature in a He or H ₂ air flow and maintained at that temperature.

When the temperature of the heat generating material (7) is raised to 700 ° C., which is lower than the melting point of nickel (Ni), a very large heat generation phenomenon (excess heat generation) occurs in the case of H ₂ flow as compared with the case of He flow. ) Was continuously confirmed. That is, the heat generating material (7) also has a very large heat generation phenomenon (excess heat) due to contact of these metals with hydrogen gas (H ₂ ) at a temperature below the melting point of the second metal, nickel (Ni). It was confirmed that it is a material that continuously indicates (occurrence). The excess heat (Δ) generated during the holding time in this measurement was Δ = 170 [mW / g heat generating material].

[Comparative Example 1]
Using nickel (Ni) powder, which is known to be a hydrogen storage metal at high temperature, hydrogen gas (H ₂ ) flow or helium gas (He) flow conditions under the same measurement conditions as in Example 1 described above. The differential scanning calorimetry (DSC) measurement below was performed.

The results are shown in FIG. As shown in FIG. 7, for the nickel (Ni) powder, even when the temperature was raised to 700 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow.

[Comparative Example 2]
Using aluminum (Al) powder, differential scanning calorimetry (DSC) measurement was performed under the same measurement conditions as in Example 1 described above under the conditions of hydrogen gas (H ₂ ) flow or helium gas (He) flow.

The results are shown in FIG. As shown in FIG. 8, for the aluminum (Al) powder, even if the temperature was raised to 700 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow.

[Comparative Example 3]
Hydrogen gas (H ₂ ) flow or helium gas (He) flow conditions under the same measurement conditions as in Example 1 described above except that the holding temperature was set to 300 ° C. using zirconium oxide (ZrO ₂ ) powder. The differential scanning calorific value (DSC) measurement was carried out in. As a result, for the zirconium oxide (ZrO ₂ ) powder, even if the temperature was raised to 300 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow.

[Comparative Example 4]
Hydrogen gas (H ₂ ) flow or helium gas (He) flow conditions under the same measurement conditions as in Example 1 described above except that the holding temperature was set to 300 ° C. using silver dioxide (AgO ₂ ) powder. The differential scanning calorimetry (DSC) was measured in. As a result, regarding the powder of silver dioxide (AgO ₂ ), even if the temperature was raised to 300 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow.

[Comparative Example 5]
(Preparation of heat generating material (8))
The heat generating material (8) was prepared by the same method as in Example 1 described above, except that silver (Ag) was used instead of nickel (Ni) as the second metal. Here, since the melting point of aluminum (Al) is 660.3 ° C. and the melting point of silver (Ag) is 961.8 ° C., aluminum (Al) is the first metal in the heat generating material (8). Yes, silver (Ag) is the second metal.

(Measurement of differential scanning calorimetry (DSC) of heat generating material (8))
For the heat generating material (8) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above. As a result, with respect to the heat generating material (8), even if the temperature was raised to 700 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow. It is considered that this is because the hydrogen solubility of silver (Ag) was too small to occlude a sufficient amount of hydrogen.

[Comparative Example 6]
(Preparation of heat generating material (9))
The heat generating material (9) was prepared by the same method as in Example 1 described above, except that copper (Cu) was used instead of nickel (Ni) as the second metal. Here, since the melting point of aluminum (Al) is 660.3 ° C. and the melting point of copper (Cu) is 1085 ° C., aluminum (Al) is the first metal in the heat generating material (9). Copper (Cu) is the second metal.

(Measurement of differential scanning calorimetry (DSC) of heat generating material (9))
For the heat generating material (9) prepared above, differential scanning calorimetry (DSC) measurement was carried out under the same measurement conditions as in Example 1 described above. As a result, regarding the heat generating material (9), even if the temperature was raised to 700 ° C., no larger heat generation phenomenon was confirmed in the case of H ₂ flow than in the case of He flow. It is considered that this is because the hydrogen solubility of copper was too small to occlude a sufficient amount of hydrogen.

Summarizing the above results, according to the heat-generating material according to the present invention, the heat-generating material is heated to a temperature lower than the melting point of the second metal constituting the heat-generating material in the presence of hydrogen gas (H ₂ ). As a result, it was found that a very large heat generation phenomenon (generation of excess heat) can be continuously generated. It was also confirmed that the mechanism cannot be explained by the heat of hydrogen storage during a mere hydrogen storage reaction. As described above, it can be said that the heat-generating material according to the present invention has great potential for applications such as heat-generating systems.

This application is based on Japanese Patent Application No. 2018-194469 filed on October 15, 2018, the disclosure of which is incorporated by reference in its entirety.

10 Heat-generating material,
20 Aluminum (Al),
30 Nickel (Ni)
40 Alloy of aluminum (Al) and nickel (Ni),
An outer shell made of 50 silica.

Claims (10)

A first metal having a melting point of 230 ° C or higher,
A second metal having a melting point higher than that of the first metal,
Including
At this time, at least one of the first metal or the second metal has a hydrogen solubility higher than that of silver at a temperature lower than the melting point of the second metal, and the first metal or the first metal. At least one hydride of the metal of 2 has a standard enthalpy of formation greater than or equal to the standard enthalpy of CaH ₂ .
A heat-generating material (excluding those containing lanthanum) that generates heat when the first metal and the second metal come into contact with hydrogen gas at a temperature below the melting point of the second metal. The heat generating material according to claim 1, wherein the first metal and the second metal exist in the state of an alloy having a plurality of phases having different composition ratios. The heat generating material according to claim 1 or 2, wherein the first metal is aluminum, tin or lead. The heat-generating material according to any one of claims 1 to 3, wherein the second metal is nickel, titanium, zirconium, manganese, zinc, vanadium or calcium. Claims 1 to 1, wherein the combination of the first metal and the second metal is nickel-zyrosine, aluminum-nickel, aluminum-titanium, aluminum-manganese, aluminum-zinc, tin-titanium or aluminum-calcium. The heat generating material according to any one of 4. The heat-generating material according to any one of claims 1 to 5, wherein the first metal and the second metal are located inside an outer shell made of an inorganic porous body. The heat generating material according to claim 6, wherein the inorganic porous body contains a metal oxide. The heat generating material according to claim 7, wherein the metal oxide contains silica or zirconia. A heat generating device in which the heat generating material according to any one of claims 1 to 8 is arranged, and a heat generating device.
A heater that heats the heat-generating material and
A hydrogen gas supply device that supplies hydrogen gas to the heat-generating material,
Equipped with a heat generation system. The heat generating material according to any one of claims 1 to 8 is heated to a temperature equal to or higher than the melting point of the first metal and lower than the melting point of the second metal in the presence of hydrogen gas. A method of supplying heat, including heating the material.

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